Semiconducting and Metallic States in Conducting Organic Low‐dimensional Materials

Schmeißer, Dieter; Bätz, P.; Göpel, Wolfgang; Jaegermann, Wolfram; Pettenkofer, C.; Wachtel, H.; Jimenez-Gonzales, A.; Schütz, J.U. von; Wolf, H. C.; Taborski, J.; Wüstenhagen, V.; Umbach, E.; Erk, Peter; Meixner, H.; Hünig, Siegfried

doi:10.1002/bbpc.19910951124

Cited by 9 publications

(6 citation statements)

References 25 publications

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“…CN-Resonances . In terms of the building-block picture it is suggestive to subdivide the resonances of DMe-DCNQI into a cyano part (CN) and the chinone-imine-rest as already proposed in previous publications of NEXAFS results. , However, no angle resolved data have been published yet before. Resonances 1−3 of the C 1s data were attributed to the quinone ring, and resonance 4 to the cyano group in comparison with literature data on CN or CN containing molecules. − This assignment is confirmed to some extent by the here presented angular dependence of the resonances and by comparison with similar molecules.…”

Section: Resultsmentioning

confidence: 83%

Near Edge X-ray Absorption Fine Structure Resonances of Quinoide Molecules

et al. 2000

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We report on C 1s and N 1s near-edge X-ray absorption (NEXAFS) investigations of highly oriented ultrathin films of 2,5-dimethyl-N,N‘-dicyanoquinonediimine (DMe-DCNQI), tetracyano-quinonedimethane (TCNQ), and 2,5-dimethyl-1,4-benzoquinone (DMe-BQ) adsorbed on Ag(111). Several sharp resonances are resolved in the spectra indicating the localized electronic structure of these quinoide molecules. The comparison of the angle-dependent DMe-DCNQI results with those from other molecules and literature data on cyano-containing molecules leads to the conclusion that the common building-block approach is not sufficient, but that the interpretation of most valence orbitals being delocalized within the whole molecule appears to be more appropriate as confirmed by semiempirical INDO/S SDCI calculations. The NEXAFS spectra of the related DMe-DCNQI charge transfer salts also reflect strongly delocalized molecular orbitals very different from those of unreacted DCNQI.

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Section: Resultsmentioning

confidence: 83%

Near Edge X-ray Absorption Fine Structure Resonances of Quinoide Molecules

et al. 2000

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“…Thorough spectroscopical investigations are reported for films of DMe-DCNQI on surfaces of Ag(111), Ag (100) and Cu(111), Cu(110). ,,− The same protocol was applied to surfaces of alkali metals, freshly prepared on an inert support. ,,,, In all cases, highly structured films are obtained, variable by the conditions applied, including annealing, which may produce the corresponding anion radical metal salts in highly ordered arrangements. Strong pressure dependence of conductivity and oxygen adsorption 192 of such [DMe-DCNQI] 2 Cu layers on copper may be of practical importance.…”

Section: 32 Alloys With Different Dcnqi Ligandsmentioning

confidence: 99%

“…Because of their nearly 3d conductivity, the corresponding Cu salts behave quite differently. ,,,,,,− In the conducting region, these copper salts are ESR silent caused by extreme line broadening due to 3d movement of the electrons by coupling with the Cu d states. Below the M→I transition, ESR line widths narrow strongly with losing their intensity (together with conducting, which means spin pairing).…”

Section: 32 Alloys With Different Dcnqi Ligandsmentioning

confidence: 99%

“…51 Thorough spectroscopical investigations are reported for films of DMe-DCNQI on surfaces of Ag (111), Ag (100) and Cu (111), Cu (110). 36,192,[216][217][218][219][220][221][222][223][224][225][226] The same protocol was applied to surfaces of alkali metals, freshly prepared on an inert support. 219,220,222,227,228 In all cases, highly structured films are obtained, variable by the conditions applied, including annealing, which may produce the corresponding anion radical metal salts in highly ordered arrangements.…”

Section: Thin Films Of Dcnqi Type Acceptors and Their Saltsmentioning

confidence: 99%

“…Because of their nearly 3d conductivity, the corresponding Cu salts behave quite differently. 4,33,95,102,266,267,[270][271][272][273][274] In the conducting region, with localized spin states. Magnetic measurements have been applied to DCNQI type copper salts mostly in combination with ESR spectroscopy.…”

Section: Evaluation Of the Electronic State Of Dcnqi Type Anion Radic...mentioning

confidence: 99%

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N,N‘-Dicyanoquinone Diimines (DCNQIs): Versatile Acceptors for Organic Conductors

Hünig

Herberth

2004

Chem. Rev.

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2,5-DisubstitutedN,N′-Dicyanobenzoquinonediimines (DCNQIs): Charge-Transfer Complexes and Radical-Anion Salts and Copper Salts with Ligand Alloys: Syntheses, Structures and Conductivities

Hünig¹,

Kemmer²,

Meixner³

et al. 1999

Eur. J. Inorg. Chem.

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The new members of the series of 2,5‐disubstituted DCNQIs, 1d (Cl/OMe), 1e (Br/OMe), 1j (Cl/I), 1k (Br/I), 1l (I/I), form conducting charge‐transfer complexes with TTF (tetrathiofulvalene) which are comparable to known DCNQI/TTFs. From these DCNQIs highly conducting radical‐anion salts [2‐X, 5‐Y‐DCNQI]2M (M = Li, Na, K, NH4, Tl, Rb, Ag, Cu) can also be prepared either from the DCNQIs and MI (not AgI), on a metal wire (Ag, Cu), or by electrocrystallization (M = Tl, Ag,Cu). For better crystals a method using periodical switching between reduction and partial oxidation has been developed. With CF3 (large, strongly electron‐attracting) as the substituent in DCNQIs 1m (OMe/CF3) and 1n (Me/CF3), conducting TTF complexes remain whereas only 1n yields an insulating copper salt. DCNQI–Cu salts with high conductivities are obtained with alloys containing two or three different DCNQIs. The temperature‐dependent conductivities of DCNQI–M salts (other than copper) are similar to those of metal‐like semiconductors. All new DCNQI–Cu salts are metallic [M] down to low temperatures, except [1d (Cl/OMe)]2Cu which undergoes a sharp phase transition to an insulating state[M → I]. By variation of the ligands or their ratios in conducting alloys of DCNQI–Cu salts temperature‐dependent conductivities can be tuned from M → I to M. In addition, alloying three ligands produced for the first time a radical salt with temperature‐independent conductivity from 5 to 300 K. Most remarkably, alloys of the type [(2,5‐Me2DCNQI)m] Cu/[{2,5‐(CD3)2‐DCNQI}n]2Cu which exhibit a sharp M → I phase transition on further cooling reenter the conducting state by an I → M transition, with changes of ca. 108 Scm−1 both ways. For the first time in the field of organic metals crystal structures of DCNQI–copper salts have been determined by X‐ray powder diffraction methods and refined by Rietveld analysis. Unit cell data, coordination angles and distances of the π planes are in excellent agreement with the single‐crystal X‐ray data. However, bond lengths and angles of the ligands are to be less accurate. This powder method proves to be most valuable if only microcrystalline material is available.

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Semiconducting and Metallic States in Conducting Organic Low‐dimensional Materials

Cited by 9 publications

References 25 publications

Near Edge X-ray Absorption Fine Structure Resonances of Quinoide Molecules

Near Edge X-ray Absorption Fine Structure Resonances of Quinoide Molecules

N,N‘-Dicyanoquinone Diimines (DCNQIs): Versatile Acceptors for Organic Conductors

2,5-DisubstitutedN,N′-Dicyanobenzoquinonediimines (DCNQIs): Charge-Transfer Complexes and Radical-Anion Salts and Copper Salts with Ligand Alloys: Syntheses, Structures and Conductivities

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